Distillation of acid-treated cashew



Patented July 10, 1951 DISTILLATION F ACID-TREATED CASHEW NUT SHELL LIQUID Solomon Caplan, New York, N. Y., assignor to The Harvel Corporation, a corporation of New Jersey No Drawing. Application January 27, 1948, Serial No. 4,713

3 Claims.

This invention relates to novel methods of processing cashew nut shell liquid and to novel products produced thereby. More particularly this invention is directed tonovel methods of processing cashew nut shell liquid in the production of distillates and residues thereof and to novel products produced thereby.

In the course of my experimentations with raw cashew nut shell liquid, I- have discovered that the color as well as the color stability of the distillates recovered therefrom may be greatly enhanced, the percentage of clear distillates obtained therefrom may be materially increased and the viscosity at 25 C. of the residues obtained therefrom may be greatly reduced even when they measure less than 45% by weight based on the weight of the cashew nut shell liquid from which they have been derived. These improved distillates and residues may be obtained from cashew nut shell liquid starting material having particular and predetermined charshell liquid is intimately mixed with said aqueous solution of an acidic agent, whereupon the mineral components and also the nitrogenous components react with or form addition products or salts with the acidic agent and dissolve in the aqueous medium. This treatment of the raw cashew nut shell liquid with the said acidic agent may be conducted at temperatures-between that inst slightly above the freezing point of water and 350 F. and under atmospheric pressure as well as superatmospheric pressure conditions.

However, I prefer that this treatment be can'- ducted at atmospheric pressure and temperatures .ac'teristics compared to the characteristics of the cashew nut shell liquid from which it has been derived. The starting material, which is subjected to distillation so that these improved distillates and residues may be obtained, is treated cashew nut shell liquid substantially free from the nitrogenous and mineral components normally present in raw cashew nut shell liquid and having a viscosity at 25 C. no greater than that 4 of the raw cashew nut shell liquid at the same temperature. Besides obtaining these novel products therefrom, the distillation procedure is more uniform and in addition there is substant'ially no foaming during the process.

' The starting material may be prepared in the manner described in my application of even date Serial No. 4,695. As described therein, a quantity of cashew nut shell liquid is mixed with an aqueous solution of an acidic agent having an ionization constant at least as great as l.75 Illustrative examples of said agents are acetic acid, hydrochloric acid, sulphuric acid, sodium acid sulphate, etc. The concentration of said acidic agent in said aqueous solution is below that necessary to cause appreciable polymerization or thickening of the raw cashew nut shell liquid under the conditions of treatment which may vary. The ratio by weight in said mixture of said acidic agent to the raw cashew nut shell liquid therein is the chemical equivalent of at least .2 part of sulphuric acid to 100 of cashew nut between 60-210 F. Then if no.external heat has been applied the mass is heated to a temperature between 120-210 F. in order to break any emulsion which may have formed during the mixing step and the mass is allowed to stand.- wherebyit cools 'to room temperature and sex arates into two main layers, an aqueous layer shell liquid and preferably .4 part of sulphuric acid to of cashew nut shell liquid and may be as high as desired, although in factory pracand 9, treated cashew nut shell liquid layer. After the separation has been attained, the treated cashew nut shell liquid containing 0-2% water is removed from the aqueous layer in any desired manner, by drawing on either the treated cashew nut shell liquid layer or the aqueous layer, for example. This aqueous layer now contains in solution the salts of mineral and nitrogenous components originally present in the raw cashew nut shell liquid. If desired, the entire procedure may be carried out at room temperature without the application of any externalheat. When no heat is employed, emulsions are formed and they may be'centrifuged, whereby the resultant treated cashew nut shell liquid containing 0-2% water is removed from the aqueous component.

When it is not desired to use the centrifuging step, a sharp separation may be obtained by employing an organic solvent for the treated cashew. nut shell liquid. In any case, the aqueous component is removed from the cashew nut shell liquid phase and contains the mineral and nitrogenous components of raw cashew nut shell liquid, all of which are in solution in the water. The nitrogenous compounds may be recoveredfrom the aqueous solution if desired. When no organic solvent is used, the cashew nut shell liquid phase which has been separated from the aqueous solution usually contains -2% of water. This product is heated under reduced pressure conditions to drive 011 the water without increasing the viscosity at 25 C. above that of the raw cashew nut shell liquid. Generally temperatures of 200-220 F. and pressures below 50 mm. of mercury pressure are employed for this purpose. During the treatment of the raw cashew nut shell liquid as well as the removal of the treated cashew nut shell liquid which is the non-aqueous phase from the aqueous phase, the pH of the-aqueous phase is always maintained at a value never below that of the aqueous solution of the acidic agent mixed with the cashew nut shell liquid and preferably above that necessary to increase the viscosity at 25 C. above that of raw cashew nut shell liquid at 25 C. when the mixture is maintained at 200 F. for 3 hours. By removing the aqueous phase in these various ways, nitrogenous and mineral components of raw cashew nut shell liquid and/or reaction or addition products of said components with the acidic agent are in solution in said aqueous phase and consequently are removed as part thereof. In this way, the aqueous phase is removed from the cashew nut shell liquid without decreasing the pH of the aqueous phase.

The raw cashew nut shell liquid which may be treated according to this invention is any raw cashew nut shell liquid however obtainedand whether partially or completely decarboxylated. It may be the raw cashew nut shell liquid containing a large proportion of anacardic acid and obtained by the extraction of cashew nut shell liquid by the cold extraction or solvent extraction method or it may be the cashew nut shell liquid of commerce generally obtained by the hot extraction method of the type set forth in the U. S. patent to E. R. Hughes, No. 2,058,456 and containing a very small percentage of anacardic acid, or it may be either of these particular types which have been partially or completely decarboxylated.

The following Examples l-8 are given by way of illustrating specific ways of producing the starting materials but are not to be regarded in alimiting sense:

Example 1 500 grams raw cashew nut shell liquid 200 grams aqueous solution H1804 containing 10% H2804 are placed in a lead lined autoclave equipped with an agitator. The mixture is heated with constant stirring to a temperature of about 300-325" F. whereupon the guage pressure indicates 70 lbs. per square inch. The heating and stirring are stopped and the mass is allowed to cool to room temperature. The mass is then found to have separated into two main layers: an aqueous layer and a non-aqueous layer of cashew nut shell liquid. The aqueous layer is drawn oil. A comparison of the viscosity of the raw cashew nut shell liquid with that of the sotreated cashew nut shell liquid is as follows:

Viscosity of raw cashew nut 500 grams raw cashew nut shell liquid 200 grams aqueous solution H2804 containing 5% H1504 are placed in an autoclave and heated therein with constant stirring until the pressure is 55 lbs. per square inch. Heating and stirring are stopped and the mass is allowed to cool to room temperature whereupon it separates into two main layers: an aqueous layer and a nonaqueous cashew nut shell liquid layer. The aqueous layer is removed. A comparison of the viscosity of the raw cashew nut shell liquid with that of the so-treated cashew nut shell liquid shows:

Viscosity of raw cashew nut shell liquid. 265 cp. at 25 C. Viscosity of treated cashew nut shell liquid 188 cp. at 25 C.

Example 3 500 grams raw cashew nut shell liquid are treated with 200 grams of an aqueous solution of H2804 containing 2% H2804 in the same manner as that set forth in Example 2. A comparison of the viscosity of the raw cashew nut shell liquid with that of the so-treated cashew nut shell liquid gave the following results:

Viscosity of raw cashew nut shell liquid 222 cp. at 25 C. Viscosity of treated cashew nut shell liquid 124 cp. at 25 C.

Example 4 500 grams of raw cashew nut shell liquid are treated with 200 grams aqueous solution of HCl containing 10% B01 in the same manner as that set forth in Example 2. Comparison of the viscosity oi the raw cashew nut shell liquid with that of the treated cashew nut shell liquid showed:

Viscosity of raw cashew nut shell liquid 222 cp. at 25 C. Viscosity of treated cashew nut shell liquid 184 cp. at 25 C.

Example 5 Treated cashew nut shell liquids were produced whose viscosities were in every instance lower than that of the raw cashew nut shellliquid employed.

Example 6 The proportions of materials being the same as those set forth in the preceding examples and carrying out the mixing at room temperature in each instance and then thereafter breaking the resultant emulsions by heating preferably at a temperature between -2l0 F. and then allowing the mass to stand, it will separate into two main layers. After the water layer has been removed in each instance the resultant so-treated cashew nut shell liquid will be found to have a reduction in viscosity of more than 10% when compared to the viscosity of the raw cashew nut shell liquid employed.

Example 7 4 lbs. concentrated H2304 were dissolved in 100 lbs. water and this solution was added to 400 lbs.

sure conditions and at a temperature below 200.

F. whereupon the solvents were distilled off leaving behind a treated cashew nut shell liquid. A

6 of the raw cashew nut shell liquid from which it was derived. One method, for example is to heat the treated cashew nut shell liquid atv about 200 F. under reduced pressure of below 50 mm. of

mercury. Another method is to heat a layer of treated cashew nut shell liquid for a short period at 300? F. In any case the time of heating is such that the water is completely eliminated therefrom without increasing its viscosity at 25 C. above that of the raw cashew nut shell liquid from which it was derived. According to this invention the treated cashew nut shell liquid is distilled at elevated temperatures and under reduced pressure to provide novel comparison of the viscosity of the raw cashew nut shell liquid with the treated cashew nut shell liquid showed:

Viscosity of raw cashew nut shell liquid 265 cp. at C. Viscosity of treated cashew nut shell liquid 160 cp. at 25 c.

Example 8 75 lbs. of concentrated H2804 were dissolved in 2500 lbs. of water and this solution was added to 6200 lbs. of raw cashew nut shell liquid at room temperature. This mixture was thoroughly agitated for about two hours during which time the temperature of the mass was increased to about 200 F. Then agitation was stopped and heating continued to maintain the temperature of the mass at 200 F. for an additional 4 hours. Then the external heat was removed and the .and improved distillates and residues.

In carrying out this invention, I prefer that the treated cashew nut shell liquid be completely dehydrated before proceeding with 'the distillation, and with care being taken in the dehydration step-so that the viscosity of the completely dehydrated product be'no greater than the raw cashew nut shell liquid from which it was derived. The distilla- Y tion is preferably carried out in a temperature range of 475 to 580 F. and at a reduced p'ressure no greater than 20 mm. and generally 1-15 mm. of mercury pressure. By following this procedure it is possible to obtain distillates having boiling point of approximately 225 C. at 10 mm. of mercury pressure and consisting chiefly of anacardic phenol, generally characterized as phenol having in the meta position 15 carbon atom unsaturated hydrocarbon substituents,whose unsatmass was allowed to cool overnight whereupon it separated into two main layers: an aqueous and a treated cashew nut shell liquid layer. The cashew nut shell liquid was removed from. the aqueous layer. the raw cashew nut shell liquid with that of the treated cashew nutshellliquid showedz Viscosity of raw cashew nut Comparison of the viscosity of.

uration is due to one or more ethylenic'linkages.

The surprising advantages inherent in'the'employment of said treated cashew nut shell" liquids in the production of the distillates and residues are (1) the recovery of high percentage of distillate which may be more than of the'wei'ght of the treated cashew nut shell liquid being. distilled, of said distillate which is of light color and has relatively good color stability, (2) therecovcry of residues liquid atroom temperature. even when the-percentage of residue is as low, as' '55% of the weight of the treated cashew nut shell liquid being distilled, (3) lower temperatures may be employed to recover a particular quantity of distillate when operating under the same presshell liquid 436 cp. at 25C.

Viscosity of treated cashew nut shell liquid 244 cp. at 25 C.

By following the teachingsof this invention as exemplified in Examples 1-8 there may be produced treated cashew nut shell liquid which is substantially free of the nitrogenous and mineral components normally present in raw cashew nut shell liquid and having a viscosity characteristic at 25 C. no greater than that of the raw cashew nut shell liquid before the removal of said components therefrom.

The various treated cashew nut shell liquids of Examples 1-8 are substantially free of water and also of nitrogenous and mineral components normally present in raw cashew nut shell liquid and capable of being precipitated by means of diethyl sulphate. If it is desired to remove all I traces of those components, the treated cashew nut shell liquid of Examples 1-6 and 8 may be water washed one or more times. If it is desired to remove all traces of water which may be present, the cashew nut shell liquid of Examples 1-6 and s which may or may not have been water washed may be processed in various ways whereby they may be completely dehydrated without increasing the viscosity thereof at 25 0. above that sure conditions, (4) the time of distillation may be greatly reduced, (5) a clear solution may be obtained when only four parts of one of said distillates is combined with 1 part of Derris resin (rotenone containing insecticidal agent derived from Derris root) and diluted with ten volumes of a hydrocarbon mineral oil fraction, such as kerosene, (6) the distillates may be more readily hydrogenated, (7) there is a very low loss of volatiles.

The following is an example which is given merely to illustrate the invention and is not to be regarded in a limiting sense because any of the treated cashew nut shell liquids .might be employed to provide the novel distillates and residues by following the general procedure of, this example where comparatively low temperatures are employed and time of distillation is comparatively short for the production of large percent ages of distillates.

Example 9 500 grams of the treated cashew nut shell liquid having a viscosity of ,160centipoises at 25 C. and produced according to Example 7 was placed in a two liter flask connected to a vacuum lineand to a condenser terminating in a receiving chamber. a The pressure within the flask was reduced and the temperature of the mass therein Temperature Mm of Hg Time h 3:; pressure in Remarks the flask the flask Distillation begins.

Shut of! gas.

The distillate collected was light straw color and had excellent color stability darkening only slightly in the course of several weeks. The quantity of said distillate collected measured 310 grams. The residue was liquid at room temperature and measured 186 grams. There was a loss oi only 4 grams.

I claim:

1. The method comprising distilling treated cashew nut shell liquid substantially free of nitrogenous and mineral components normally present in raw cashew nut shell liquid and whose viscosity at 25 C. is no greater than that of the raw cashew nut shell liquid. said distillation carried out under reduced pressure and at elevated temperature and collecting phenolic constituent having an unsaturated hydrocarbon substituent of 15 carbon atoms; said treated cashew nut shell liquid produced by removing from raw cashew nut shell liquid nitrogenous and mineral components normally present therein by mixing said raw cashew nut shell liquid with an aqueous solutionof an acidic agent, the ionization constant of said agent being at least 1.75 l0 the ratio by weight of said acidic agent to said cashew nut shell liquid of said mix being the chemical equivalent of at least 0.2 part of H2504 to 100, the ratio by weight of the quantity of water in said solution to the quantity of said cashew nut shell liquid being at least 10-100, the concentration of said acidic agent in said solution being below that necessary to increase the viscosity of the cashew nut shell liquid at 25 C. when maintained at 200 F. for 3 hours, and then removing from said mass said treated cashew nut shell liquid whose viscosity at 25 C. is no greater than that of said raw cashew 'nut shell liquid at the same temperature.

2. The method comprising distilling treated cashew nut shell liquid substantially free or nitrogenous and mineral components normally present in raw cashew nut shell liquid and whose viscosity at 25 C. is no greater than that of the raw cashew nut shell liquid, said distillation carried out at temperatures of 475 F. to 580 F. and reduced pressureno greater than 20 mm. of mercury pressure; said treated cashew nut shell liquid produced by removing from raw cashew nut shell liquid nitrogenous and mineral components normally present; therein by mixing said raw cashew nut shell liquid with an aqueous solution of an acidic agent; the ionization constant of said agent being at least 1315x10 the ratio by weight 01' said acidic agent to said cashew nut shell liquid of said'mix being the chemical equivalent of at least 0.2 part of H2804 to 100, the ratio by weight of the quantity of water in said solution to the quantity of said cashew nut shell liquid being at least 10-100, the concentration of said acidic agent in said solution being below that necessary to increase the viscosity of the cashew nut shell liquid'at 25 C. when maintained at 200 F. for 3 hours, and then removing from said a REFERENCES CITED The following references are oi record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,128,24'1 Harvey Aug. 30, 1938 2,447,432 Schaufelberger Aug. 17, 1948 

1. THE METHOD COMPRISING DISTILLING TREATED CASHEW NUT SHELL LIQUD SUBSTANTIALLY FREE OF NITROGENOUS AND MINERAL COMPONENTS NORMALLY PRESENT IN RAW CASHEW NUT SHELL LIQUID AND WHOSE VISCOSITY AT 25* C. IS NO GREATER THAN THAT OF THE RAW CASHEW NUT SHELL LIQUID, SAID DISTILLATION CARRIED OUT UNDER REDUCED PRESSURE AND AT ELEVATED TEMPERATURE AND COLECTING PHENOLIC CONSTITUENT HAVING AN UNSATURATED HYDROCARBON SUBSTITUENT OF 15 CARBON ATOMS; SAID TREATED CASHEW NUT SHELL LIQID PRODUCED BY REMOVING FROM RAW CASHEW NUT SHELL LIQUID NITROGENOUS AND MINERAL COMPONENTS NORMALLY PRESENT THEREIN BY MIXING SAID RAW CASHEW NUT SHELL LIQUID WITH AN AQUEOUS SOLUTION OF AN ACIDIC AGENT, THE IONIZATION CONSTANT OF SAID AGENT BEING AT LEAST 1.75X10-5, THE RATIO BY WEIGHT OF SAID ACIDIC AGENT TO SAID CASHEW NUT SHELL LIQUID OF SAID MIX BEING THE CHEMICAL EQUIVALENT OF AT LEAST 0.2 PART OF H2SO4 TO 100, THE RATIO BY WEIGHT OF THE QUANTITY OF WATER IN SAID SOLUTION TO THE QUANTITY OF SAID CASHEW NUT SHELL LIQUID BEING AT LEAST 10-100, THE CONCENTRATION OF SAID ACIDIC AGENT IN SAID SOLUTION BEING BELOW THAT NECESSARY TO INCREASE THE VISCOSITY OF THE CASHEW NUT SHELL LIQUID AT 25* C. WHEN MAINTAINED AT 200* F. FOR 3 HOURS, AND THEN REMOVING FROM SAID MASS SAID TREATED CASHEW NUT SHELL LIQUID WHOSE VISCOSITY AT 25* C. IS NO GREATER THAN THAT OF SAID RAW CASHEW NUT SHELL LIQUID AT THE SAME TEMPERATURE. 